This invention has to do with apparatus for enhancing the combustion process in internal combustion engines by introduction of suitable additives in vaporized form into the air stream entering the engine.
It has long been recognized that injection of a vaporized additive, such as water or an alternative fuel, for example, can modify the combustion process in a useful way. Addition of water vapor to the combustion mixture tends to retard the combustion rate, permitting higher compression ratios without such conventional gasoline additives as lead compounds. Injection of vaporized water at high temperature further promotes complete vaporization of the conventional fuel, producing more complete combustion and affording better control of undesired exhaust emissions. Potentially useful supplemental fuels, such as alcohol, for example, when in liquid phase are soluble in gasoline only to a limited extent, but can be introduced in virtually arbitrary proportions when vaporized and added to the air stream downstream of the carburetor.
Numerous mechanisms have been proposed for controlling the supply of such additives to the fuel mixture of an internal combustion engine in response to varying conditions of engine operation. However, there has been little agreement as to the most desirable control action, and many of the proposed control mechanisms appear to have been only marginally effective in producing the particular action that was intended.
We have found that optimum enhancement of the combustion process requires accurate control of the rate at which an additive is supplied, together with smooth and reliable variation of that rate in accordance with the varying conditions of engine operation. Moreover, that control should extend with sensitive response and with accurate repeatability over the entire operating range of the engine.
More particularly, we have found that, although a typical engine requires little or no additive when idling, even a very light load, or a slight increase in engine speed, calls for a corresponding increase in the additive supply. Thus the control mechanism must respond accurately to the condition of operation even within the range of extremely low flow rates.
Many conventional valve mechanisms are designed primarily for shifting rapidly between closed and open conditions. Although such valves necessarily progress through a multitude of partially open intermediate conditions, their transitions between such states ordinarily cannot be controlled accurately and do not occur in a strictly repeatable manner.